Ion-induced electron production in tissue-like media and DNA damage mechanisms

TL;DR

This paper presents a microscopic approach to calculating secondary electron characteristics produced by ions in tissue-like media, linking physical interactions to DNA damage mechanisms such as strand breaks and local heating.

Contribution

It introduces a novel inclusive method for analyzing secondary electron production and its biological implications, specifically relating microscopic interactions to DNA damage.

Findings

Energy spectrum and abundance of secondary electrons as functions of projectile energy

Analysis of DNA double strand breaks caused by secondary electrons and radicals

Comparison of dose-depth curves with GEANT4-based MCHIT model

Abstract

We propose an inclusive approach for calculating characteristics of secondary electrons produced by ions/protons in tissue-like media. This approach is based on an analysis of the projectile's interaction with the medium on the microscopic level. It allows us to obtain the energy spectrum and abundance of secondary electrons as functions of the projectile kinetic energy. The physical information obtained in this analysis is related to biological processes responsible for the irrepearable DNA damage induced by the projectile. In particular, we consider double strand breaks of DNA caused by secondary electrons and free radicals, and local heating in the ion's track. The heating may enhance the biological effectiveness of electron/free radical interactions with the DNA and may even be considered as an independent mechanism of DNA damage. Numerical estimates are performed for the case of carbon-ion beams. The obtained dose-depth curves are compared with results of the MCHIT model based on the GEANT4 toolkit.